Project Summary Recent advances in hardware instrumentation (microscopes, detectors), and computational software (image processing algorithms) have transformed biology by allowing for near atomic resolution analysis of large, macromolecular complexes using cryo-electron microscopy (cryo- EM). NIH-funded research programs across the University of Illinois at Urbana-Champaign (UIUC) with studies that focus on antimicrobials, antifungals, cancer, immune diseases, HIV/AIDs, among other diseases would benefit enormously from access to cryo-EM. While the campus have excellent facilities for TEM/SEM studies of materials and nanostructures, the instrumentation for cryo-EM studies of biological macromolecules is sorely lacking. Instrumentation to enable local capabilities for cryo-EM and micro-electron diffraction (microED) are necessary to advances these research programs. We request funding to partially offset the costs for a Glacios 200 kV cryo transmission electron microscope with an active pixel sensor (for microED) and direct electron detector (for cryo-EM). The Glacios will significantly impact existing NIH-funded projects by enabling studies of large multi-protein complexes, and small natural products and metabolites. The necessary intellectual expertise and operational infrastructure is already in place on the UIUC campus, providing strong justification for the requested instrumentation. The Glacios will complement the UIUC membership as part of the PI4L Consortium, which provides access to the most advanced cryo-EM instrumentation to advance structures that are first solved on the UIUC campus to the highest possible resolution.